SALT LAKE CITY – Rep. Jason Chaffetz announced Thursday he will resign from Congress next month, a move that calls into question the future of the House Oversight Committee’s investigation he promised to lead about President Donald Trump’s firing of the FBI director and his presidential campaign’s ties with Russia.

Chaffetz made the announcement a day after tweeting that he had invited ex-FBI Director James Comey to testify next week at a hearing of the oversight committee he chairs.

Comey was fired last week as the FBI investigates whether Trump’s presidential campaign associates had colluded with Russia to influence the outcome in his behalf.

The Utah Republican, who had just started his fifth term in Congress, used his post as chair of the oversight committee to doggedly investigate Hillary Clinton before the 2016 presidential election and raise his political profile.

But he mainly declined to go after Trump until this week.

On Tuesday, he vowed to get the memos ex-FBI Director James Comey reportedly wrote about his meeting with Trump in which the president allegedly asked him to shut down the FBI investigation into ousted National Security Adviser Michael Flynn.

His letter announcing his resignation did not mention the investigation, focusing solely about his decision about wanting to spend more time with family. It was not immediately clear how the House Oversight Committee would proceed.

Chaffetz said his last day will be June 30. His announcement came after he said last month he would not seek re-election in 2018 and was considering leaving his post before his current term ends.

The former kicker for the Mormon-owned Brigham Young University football team was first elected to the U.S. House of Representatives in 2008. He strolled to four-easy re-elections in his Republican-friendly district and became chairman of the house oversight committee in 2015.

He has not ruled out running for another office, such as Utah governor.

Prior to his time in office, he worked in communications for more than a decade and served as campaign manager for former Utah Gov. Jon Huntsman, Jr.